Alcohols 4a,bderived from ketone 3 were transformed, in acidic medium, to the rearranged compounds 6 (or 6′) and to the pentacyclic derivative 8. This procedure provides easy access to the 16-deethylapovincamine skeleton.
The 2-oxo functionalized title compound 1 was synthesised in 7 steps from tryptamine via rearrangement of the bromoiminium ion 13 in alkaline medium to azepinone 14 with concomitant formation of ketone 15. The ratio 14:15 was shown to depend on the nature of the hydroxide counterion.